Hafner AR III 1:5 (6) - RC Groups
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Aug 26, 2017, 08:54 AM
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Build Log

Hafner AR III 1:5 (6)


I am planning to build a Hafner AR III Gyroplane in scale 1:5 (maybe 1:6).
Size would be 108cm fuselage length and 200cm rotor diameter.
Aiming at a weight of around 2.5kg even a 160cm rotor should be enough.

Having taken my last project to a success I now wanted to try something bigger.
Problem: I have no experience with big planes, let alone autogyros
There has been already discussion about hte Hafner
https://www.rcgroups.com/forums/show...Gyroplane-info

So far I modeled the fuselage in PowerPoint and Devfus.
For the rotorblades balsa profiles are ordered.
https://www.lindinger.at/de/?sViewpo...rofilbrettchen
I plan to give those a 2.5mm steal nose.

Has anybody experience regarding dimensions of a deltaplate for rotors this size??
I am thankfull for any help/suggestions I can get?
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Aug 28, 2017, 07:35 AM
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Fotos of the powerpoint sketch and the planned profil of the rotor blades
Aug 28, 2017, 06:57 PM
It's all in the Blades!
SafeLandings's Avatar
I like this auto and drew my own version up, what concerned me was the lack of vertical area and that short nose. I designed a model I called Burky to test out how a fuselage like this would react in the air and it worked fine.

I have attached my version and some photos I worked off, if its any help then please use it, one day I will get round to building it I hope.

Rich
Aug 29, 2017, 05:42 AM
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Rich, thank you for your drawings!!
The nose seems not so short to me, as the motor is placed in front of the fuselage. To my measurement distance from prop to mast (vertical) equals roughly the mast hight. This is a relation that seems to work OK. Isnīt it?
My plan is, to build the rotor and hub first and test it on a robust prototype fuselage (styro or EPP). Once I am more familiar with the behavior of a rotor this size and the model flyes OK, I might build a nicer scale fuselage.
Still looking for dimensions of a delta plate. I might start with 1,5mm thinkness, 12-15 cm side length?
Sep 01, 2017, 04:06 AM
BigTradioman's Avatar
I would take a look at the DAG delta plate which has a second round plate below the plate that holds the blades. The purpose is to prevent the blades drooping before they cone up.
Sep 10, 2017, 04:35 AM
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I played a bit with DevFus software to model the fuselage.
Made a version with formers and spars, but right now I think I go first with a body made from 10mm EPP sheet as a testbed for the rotor system. The top view deviates from the topview in the available threeview sketch, but for some reason I like mine better although I am not sure why.
Still waiting for the balsa profiles.
Sep 11, 2017, 01:46 AM
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britinoz's Avatar
Oh... I'f I could only handle those tools...
Chris...
Sep 11, 2017, 03:16 AM
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No CAD expertise required. The Software makes it really easy to produce a 3D desigen of a fuselage. The downside is of course that you are not totally free to change what you like (e.g. spars fitted to diagonal formers and some others). But for people with my CAD expertise (non) it seems to be a suitable software. I have no extended experience with it, so I still have to see if it really helps me in the building process.
There is trial version available.
I have no affiliation what so ever with the people selling this product!!
Sep 11, 2017, 03:24 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
YouTube, YouTube, YouTube, YouTube, YouTube, YouTube, YouTube, YouTube, YouTube, YouTube.

YouTube Tutorials, YouTube Tutorials, YouTube Tutorials, YouTube Tutorials, YouTube Tutorials.

DevFus, FreeCAD, Fusion 360, DevFus, FreeCAD, Fusion 360, DevFus, FreeCAD, Fusion 360, DevFus, FreeCAD, Fusion 360, DevFus, FreeCAD, Fusion 360, DevFus, FreeCAD, Fusion 360.

Crate of beer/ bottle of wine/ pot of coffee, Crate of beer/ bottle of wine/ pot of coffee, Crate of beer/ bottle of wine/ pot of coffee, Crate of beer/ bottle of wine/ pot of coffee, Crate of beer/ bottle of wine/ pot of coffee, Crate of beer/ bottle of wine/ pot of coffee, Crate of beer/ bottle of wine/ pot of coffee.

Hour or so for a couple of evenings, Hour or so for a couple of evenings, Hour or so for a couple of evenings, Hour or so for a couple of evenings, Hour or so for a couple of evenings, Hour or so for a couple of evenings, Hour or so for a couple of evenings, Hour or so for a couple of evenings,

All you need Chris.

Sep 11, 2017, 08:41 PM
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britinoz's Avatar
Thanks guys.......I think that Paul is trying to tell me something...but he has not made it very clear to this poor old brain of mine.
Chris...
Sep 12, 2017, 03:27 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
My wife tells me that I irritate her by repeating myself.... it's almost as if she thinks that I don't know that I am doing it.



May her off but it gets the message across..............




Seriously, I was pleasantly surprised at how many good, easy to follow Tuts there are out there. If you can kind of picture how any 3D shape can be viewed in 2D by looking at faces and then 'pulled out' or 'extruded' to create a 3D shape you are home and dry and it is totally obvious that you can otherwise you would never have been capable of scratch building a model.

Literally a case of learning how to open the program (errr, click the icon). 'This is how to draw a square', 'click here and enter the height which you require' and hey presto, it's a cube. After that it gets a lot easier
Sep 12, 2017, 05:44 AM
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britinoz's Avatar
Thanks Paul I appreciate your help...i will investigate
Thanks
Chris...
Sep 29, 2017, 01:37 PM
Registered User
Finally the profiles for the rotorblades have been delivered.
They look quite ok, but I am not totally happy due to differences in weight.
Weights are 49.54, 57.34, 65.31 and 45.15g
I am not sure if it is reasonable to try to make a set of blades of them, or better start new with matched balsa sheets.
Sep 29, 2017, 02:03 PM
Registered User
I am also a bit disappointed with the profile consistency.
Thickness of the blunt nose varies from 1mm to almost 4mm. Total Thickness changes from 7.9 to 8.5mm.
Let's see what can be done with them.
Sep 30, 2017, 08:11 PM
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britinoz's Avatar
I would have thought that the profile should be a little more consistent,but as this wood is soft ..I'm sure that the machining is not an easy process...but in saying that ..that's what you are paying fore.
As I have been carving my own blades for many years ...I have found that by cutting one large sheet of wood into four equal size pieces...can result in four completely different weights....but there again ...possibly a manufacturer should send out blades in balanced sets?
I'm sure a sanding block will fix the problem.
Chris...


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